So-called “energy harvesters” and “energy harvesting” refer generally to apparatus and methods for collecting and storing energy present in the environment, such as heat or solar energy, RF energy, and kinetic energy such as low frequency excitation or rotation. Such energies are referred to herein as “waste” or “free” energies. Storing is typically in the form of conversion of waste energy to electricity for subsequent storage in a battery.
Electrically operated devices that are mounted in or on a door or at a remote closure, such as, for example, electric door release mechanisms, illumination devices, video screen displays, keypads and signage, are known. Electric door release mechanisms in particular, such as electrically-operated door strikes or door locks, are useful in providing remote or hands-free unlocking operation of a door in a frame, or for providing selective security for items within an area bounded by such a door. In the most general prior art, an electric door release mechanism is powered by a remote electric source, such as an AC grid, connected by a cable, through a transformer, to the unlocking device. The electric door release mechanism may be configured for mounting and operation in the door frame, to engage a cooperative bolt in the door, or the electric door release mechanism may be mounted in the door itself, requiring the cable to pass through the door hinge area in some fashion.
In some specialized applications wherein a power source such as an AC grid is not available or readily connectable to the electric door release mechanism, it is known to power an electric door release mechanism via a battery incorporated in or immediately proximate the door release system. Such a configuration has the disadvantage that the battery either must be kept charged in some fashion or must be replaced periodically, with risk of security failure if not timely replaced or if the recharging means fails. Further, prior art electric door release mechanisms typically are actuated by a relatively large and powerful linear solenoid or motor. Thus, where hard wiring of the mechanism from a remote power source is not possible, practical or desired, an undesirably large and expensive battery pack for operation of the electric door release mechanism is required.
What is needed in the art is an electrically operated door device such as an electric door release system wherein the power to a device can be supplied by harvesting of “waste” energy available locally.
What is further needed in the art is an electric door release system wherein the actuator requires significantly less electric power than in the prior art.
It is a principal object of the present invention to provide a secure environment wherein security is dependent upon a locally available source of waste energy, and wherein periodic human intervention is unnecessary.